• Dr. Ajay Telang
  Lecturer, Department of Oral Pathology, Penang International Dental College
  Lvl 19- 21, NB Towers. 5050, Jalan Bagan Laur, 12000, Butterworth. Penang, Malaysia
  
  
• Dr. Lahari K.
  Lecturer, Department of Oral Medicine & Radiology, Penang International Dental College
  Lvl 19- 21, NB Towers, 5050, Jalan Bagan Laur, 12000, Butterworth. Penang, Malaysia
  
  
• Dr. Pushparaja Shetty
  Prof. & Head, Department of Oral Pathology & Microbiology, A.B. Shetty Memorial Institute of Dental Sciences, Mangalore, India.
  
  Corresponding Author: Dr. Ajay Telang MDS, MSB, PGDHA
  Lecturer, Department of Oral Pathology, Penang International Dental College, Lvl 19- 21, NB Towers, 5050, Jalan Bagan Laur, 12000, Butterworth, Penang, Malaysia
  H/P - 0060129028625 - Office- 00604-3325050 - Fax - 00604-3337070
  E-mail- [email protected] - [email protected]

Introduction
A cyst is defined as a "pathological cavity having fluid, semi fluid or gaseous contents and which is not created by the accumulation of pus". Most cysts but not all are lined by epithelium. (Shear and Speight, 2007) Odontogenic cysts have been classified based on origin as inflammatory and developmental. These cysts are unique in that they only affect the maxillofacial region, arise from the embryological remnants of dental organ and have typical histopathological features. The correct diagnosis of an odontogenic cyst is important as some of them have an aggressive behavior and a propensity to recur (Jones et al., 2006).

Despite the availability of vast literature on the prevalence of maxillofacial lesions, studies focused on children have primarily been epidemiological in nature; such as the presence of caries, periodontal disease, malocclusion and trauma to teeth. Other studies in the area of oral pathology in children have concentrated on identifying odontogenic tumours or reporting a series of cases such as odontogenic tumours, jaw tumours, salivary gland tumours or salivary gland lesions. (Jones et al., 2006) Most reviews and demographic studies on odontogenic cysts are concerned with specific diagnoses such as paradental cyst, ( Philipsen & Riechart , 2004) odontogenic keratocyst ( Lam and Cahn 2000), calcifying odontogenic cyst ( Hong et al, 1991) and lateral periodontal cyst( Carter et al., 1996) in adult populations of Mexico, Canada, Germany, UK and Spain (Nuñez-Urrutia. et al.,2010)with only limited data on the prevalence of odontogenic cysts in pediatric patients.( Jones et al., 2006)

Since the epidemiology of diseases is variable between regions, the authors of this study have, therefore, carried out a survey of oral and maxillofacial pathology specimens from children aged 0-15 years submitted for diagnosis over a 19-year period (1987-2005) with the aim of determining the range of all histologically diagnosed odontogenic cysts.


Materials and Methods
The study sample comprised of all oral biopsies reported by the Dept. of Oral Pathology & Microbiology at A.B. Shetty Memorial Institute of Dental Sciences (ABSMIDS) over a period of 19 years (1987-2005). The clinical case details of patients aged 0-15years were retrieved from the archives and were reviewed. Details such as age, gender, site of biopsy and diagnosis were noted. The data thus collected was then further analyzed for the number and type of odontogenic cyst. These odontogenic cysts were further examined histopathologically and were classified into developmental and inflammatory cysts. All the data analysis and graph formations were performed using Microsoft Excel ^TM.


Results
During the 19 year period a total of 3142 specimens were received from various surgical units such as Maxillofacial surgery, Pediatric dentistry, Periodontology and Endodontics at ABSMIDS as well as Rural dental centers and a few general dental practitioners from South Canara District, Mangalore, India. Of these 172 (5.4%) specimens were pediatric oral lesions. Among these specimens, 58 (33.7%) odontogenic cysts were diagnosed in children below 15 years, 35 specimens belonged to male patients and 23 were from female patients (M: F = 1.52: 1). Figure 1 shows the gender distribution of odontogenic cysts. The common site of biopsy was the mandible with 39 cases (66.6%) and 20 cases (33.4%) were received from the maxillary region.

The largest diagnostic group was radicular cyst, which accounted for 43.2% of all odontogenic cysts (25 cases) of which 8% (2 cases) were associated with deciduous mandibular first molars while the remaining 92% (23 cases) were associated with permanent dentition. There were 16 males and 9 female patients affected giving a M: F ratio of 1.7:1.

Dentigerous cyst was the next most common diagnosis with 20.6% (12 cases) of which 66.6% (8 cases) were associated with impacted maxillary canines while the 33.4% (4 cases) were associated with mandibular premolars. There were 7 cases affecting males and 5 affecting females giving a M:F ratio of 1.4:1.

There were 5 Odontogenic keratocyst (8.6% of all odontogenic cysts) all of which were reported in the posterior mandible affecting 3 males and 2 females giving a M: F ratio of 1.5:1. Only 1case of Lateral periodontal cyst (1.7%) was diagnosed in a male patient and 15cases (25.8%) were diagnosed as cyst walls/unclassified odontogenic cysts because of the lack of clear histopathological cyst lining. Figure 2 shows the range of various types of odontogenic cysts.

Discussion
Although there is a lot of information in scientific literature about odontogenic cysts, majority of retrospective studies done on pediatric oral biopsies investigate only the occurrence of maxillofacial lesions in general. Studies done on pediatrics oral biopsies are important for two main reasons. Firstly, to know the specificity of clinical characteristics of common lesions in children and secondly, to know the incidence of oral disease in pediatric patients. (Fabricio et al., 2002) There are very few studies in the literature done exclusively on Odontogenic cysts occurring in children. Correct diagnosis of odontogenic cysts and their variants is important owing to the propensity of certain lesions to recur and have an aggressive nature.

Over the 19 year period in our study a total of 3142 specimens were received, among these 172 were pediatric oral specimens; this accounted for 5.47% of all submitted specimens which was similar to percentage of samples (5.5% to 12.8%) from other studies (Jones et al., 2006). The majority (94%) of the samples received were mainly from the maxillofacial surgery and pediatric dentistry units at ABSMIDS. While the rest of the 6% included samples from general dental practitioners and rural dental center in the region.

Our survey was limited to the age group of 0-15 years old only, although the literature showed a varied range from 0-15 yrs, 0-16 yrs and 0-18yrs. The reason we adopted the limit of 15yrs was to emphasize the incidence of cysts occurring in an early permanent dentition. The common site of biopsy was the mandible (66.6%), followed by maxilla (33.4%), which differed with findings of Salako & Taiwo (1995), who found maxilla to be the commonest site.

Radicular cyst was the most common diagnosis, accounting for 43.2% of the odontogenic cysts which was similar only to Jones & Franklin (2006) and Lawoyin (2000). While most other studies reported dentigerous cysts as the common cyst in the pediatric populations (Fabricio et al., 2002),( Salako & Taiwo, 1995),( Das & Das AK 1993), (Andrikopoulou et al., 2005),( Bodner, 2002). The reason for this difference may relate to the prevalence of caries and varied oral health regimes between different countries and regions. The present study also showed 8% radicular cysts to be associated with deciduous teeth which were higher than that documented.( Shear and Speight, 2007), ( Mass et al., 1995) According to a survey done by Shear and Speight (2007) of the 1300-documented radicular cysts only 0.5% originated from primary teeth. The frequency of radicular cysts originating from primary teeth as reflected by the number of reported cases is substantially lower than those associated with permanent teeth. The reasons cited for this include the presence of deciduous teeth for short time, easy drainage in deciduous teeth due to presence of numerous accessory canals and radiolucencies associated with deciduous teeth is being usually neglected. More over lesions tend to resolve following extraction/ exfoliation of associated tooth and generally tissue is not submitted for histopathology. (Shetty et al., 2010)

The second commonest cyst seen was the dentigerous cyst (20.6%). The incidence of which is in agreement with a few studies reported. (Fabricio et al., 2002); (Andrikopoulou et al., 2005) The tooth involved were the maxillary canine and mandibular premolars which were in accordance with previous studies.

Odontogenic Keratocyst (OKC) has also been termed as keratocystic odontogenic tumor based on the behavior of the lesion (Philipsen, 2005). However, controversy still remains between various authors regarding its classification. In our study we preferred to consider it as a cyst. We found a higher incidence of 8.6% than that reported by Fabricio et al., (2002) and Jones & Franklin (2006) but a much lower incidence than that reported by Nakamura et al., (1995) the reason being the larger age group included in the latter's review.

We found 1.7% of the odontogenic cysts to be Lateral periodontal cysts in our study, which was higher than that reported by Fabriciao et al (2002) and Das. (1993). The reason being the large number of pediatric oral biopsies reviewed. However, Jones et al., (2006) found no case of lateral periodontal cyst below the age of 20 in their study although previous studies mention that these do occur, (Lawoyin, 2000) (Fantasia, 1979).


Conclusion
The occurrence of Odontogenic cysts in our study differed from other reported studies. This may be attributed to the type of biopsies received by our institute. Owing to the fact that there are several dental clinics and private dental schools in the region, the patients get distributed and hence a comprehensive study, which includes data from other surgical pathology services of the region may best represent the actual prevalence. Yet this institutional review represents the distribution and frequency of cysts diagnosed among pediatric patients over a long period of time and highlights the predominance of radicular cyst as the most common cyst as opposed to dentigerous cyst.